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Immune 20112012

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Immune 20112012

  1. 1. IMMUNE SYSTEM
  2. 2. The immune system <ul><li>What is the main function of the immune system? </li></ul><ul><li>What is a pathogen? </li></ul>
  3. 3. The defense mechanisms <ul><li>1st line vs 2nd line vs 3rd line of defenses </li></ul>
  4. 4. Give the function of these cells <ul><li>Monocytes APC coelomocytes </li></ul><ul><li>Macrophages Basophil </li></ul><ul><li>Neutrophil Eosinophil </li></ul><ul><li>Mast cell NK cell </li></ul><ul><li>Cytokine cytotoxic T cell </li></ul><ul><li>effector cell helper T cell </li></ul><ul><li>memory cell suppressor T cell </li></ul><ul><li>T cell B cell </li></ul><ul><li>Lymphocyte granulocyte </li></ul><ul><li>Plasma cell memory cell </li></ul>
  5. 5. The chemicals and others <ul><li>Perforin Chemokine </li></ul><ul><li>Interferon antibody </li></ul><ul><li>Antigen antigen receptor </li></ul><ul><li>Cd4 Cd8 </li></ul><ul><li>Histamine Interleukin </li></ul><ul><li>Lysozyme prostaglandins </li></ul><ul><li>Pyrogens Rh factor </li></ul><ul><li>MHC genes hemolin </li></ul>
  6. 6. The innate immunity <ul><li>What happens to you if you caught a virus or an infection? </li></ul>
  7. 7. Inflammation and Sepsis <ul><li>Release of histamines (pathogen/self cell) </li></ul><ul><li>Dilation and inc permeability of BV (prostaglandin) </li></ul><ul><li>Increased blood flow </li></ul><ul><li>Inflammation (redness and swelling) </li></ul>
  8. 8. Phagocytic cells <ul><li>Neutrophils are first to arrive </li></ul><ul><li>Macrophages will also arrive </li></ul>
  9. 9. Chemokines <ul><li>Messenger chemical </li></ul><ul><li>Attracts phagocytic cells </li></ul><ul><li>Activation of lysozyme action </li></ul>
  10. 10. Severe infection <ul><li>Fever is an immune response to severe infection </li></ul><ul><ul><li>Can be caused by the pathogens </li></ul></ul><ul><ul><li>May be due to pyrogens released by some leukocytes </li></ul></ul><ul><ul><li>Can facilitate phagocytosis </li></ul></ul><ul><li>Septic shock- high fever, hypotension </li></ul>
  11. 11. Antimicrobial proteins <ul><li>Proteins that attack microbes or stall reproduction of microbes </li></ul><ul><li>Lysozyme is an example </li></ul><ul><li>Also, presence of the complement system </li></ul><ul><ul><li>Made up of 20 serum proteins </li></ul></ul><ul><ul><li>Action: lysis or attraction of phagocytic cells </li></ul></ul><ul><ul><li>Is also part of specific immune response </li></ul></ul>
  12. 12. Interferons <ul><ul><li>Secreted by virus-infected cells </li></ul></ul><ul><ul><li>Neighboring cells are stimulated to produce chemicals that can inhibit viral infection </li></ul></ul><ul><ul><li>Not virus-specific </li></ul></ul><ul><ul><li>A specific type of interferon activates phagocytes </li></ul></ul>
  13. 13. 1 Specfic Non-specific 2 Attack invaders Does not Attack invaders Lyse 3 4 antibodies 5 Attaches to APC 6 Records specific infection 7 phagocytic 8 invertebrate 9 vertebrate mature young 10 11, 12 Release histamine Kills worms 13, 14 15
  14. 14. Self vs Non-self <ul><li>Have you asked yourselves the question who am I? </li></ul>
  15. 15. Self vs Non-self <ul><li>Lymphocytes react on special surface glycoproteins encoded by genes called Major Histocompatibilty Complex (MHC) </li></ul><ul><li>In Humans, Human Leukocyte Antigens (HLA) </li></ul><ul><li>Class I MHC- Almost all nucleated cells </li></ul><ul><li>Class II MHC- macrophages, B cells, activated T cells, cell in the interior of the thymus </li></ul><ul><li>Varies from one person to another </li></ul>
  16. 16. Specific immunity: the third line of defense <ul><li>Lymphocytes- cells responsible for the specific immune response </li></ul><ul><li>There are two types: B cells and T cells (NK cells another type) </li></ul><ul><li>Antigen- molecules that elicit specific response from lymphocyte </li></ul><ul><ul><li>E.g. Molecules from bacteria, fungi, virus, parasitic worms </li></ul></ul><ul><li>Antigens activate B cell in producing antibodies </li></ul>
  17. 18. Recognition of antigens by B cells and T cells <ul><li>Specificity is possible because of membrane-bound antigen receptor </li></ul><ul><li>B cell antigen receptor- transmembrane version of antibodies </li></ul><ul><ul><li>Also called membrane antibodies </li></ul></ul><ul><li>T cell antigen receptor- called T cell receptor </li></ul><ul><ul><li>Structurally related to membrane antibodies </li></ul></ul><ul><ul><li>T cell receptor never released in secreted form </li></ul></ul>
  18. 19. Clonal selection
  19. 20. Clonal selection <ul><li>Antigen binds to a specific antigen receptor (B cell) </li></ul><ul><li>B cell produces its clone </li></ul><ul><li>Some B cells become plasma cells (short-lived) that can secrete antibodies to the specific antigen </li></ul><ul><ul><li>Plasma cells- also called effector cells </li></ul></ul><ul><li>Some B cells become memory cells (long-lived) for re-exposure to the antigen </li></ul>
  20. 21. Immunological memory <ul><li>Primary immune response- selective proliferation and differentiation of lymphocytes upon first exposure </li></ul><ul><ul><li>10-17 days to develop maximum effector cells </li></ul></ul><ul><ul><li>Selected B cells and T cells produce their respective effector cells </li></ul></ul>
  21. 22. Immunological memory <ul><li>Secondary immune response- re-exposure to the same antigen </li></ul><ul><ul><li>response is faster, greater magnitude, more prolonged </li></ul></ul><ul><ul><li>Also, more antibodies are produced </li></ul></ul><ul><ul><li>Antibodies have greater affinity to the antigens </li></ul></ul><ul><ul><li>Secondary response is called immunological memory </li></ul></ul>
  22. 23. Graph showing immunological memory
  23. 24. Lymphocyte development <ul><li>All blood cells develop from pluripotent cells </li></ul><ul><li>Lymphocytes also develop from pluripotent cells </li></ul><ul><li>T cells- mature in the thymus </li></ul><ul><li>B cells- mature in the bone marrow </li></ul>
  24. 25. Immune tolerance for self <ul><li>Maturing lymphocytes’ antigen receptors are rendered non-functional </li></ul><ul><li>If antigen receptors cannot be switched off, lymphocytes undergo apoptosis </li></ul>
  25. 26. The other cells.... <ul><li>Cytotoxic T cells- kill cells through lysis </li></ul><ul><li>Helper T cells- bind to antigen cell and secretes cytokine </li></ul><ul><li>Antigen-presenting cells (APCs)- engulf bacteria (virus) and present fragment of these pathogens to other lymphocytes </li></ul>
  26. 27. Humoral response and cell-mediated response <ul><li>Humoral immunity- involves B cell activation, production of antibodies in blood plasma and lymph called humor </li></ul><ul><li>Cell-mediated immunity- action of T cells </li></ul>
  27. 28. Overview of humoral response <ul><li>Macrophage engulfs the pathogen </li></ul><ul><li>Class II MHC binds to fragment of pathogen </li></ul><ul><li>MHC-antigen complex is presented by the phagocytic cell </li></ul><ul><li>A helper T cell with specific receptor for the antigen makes contact with the macrophage and releases cytokines </li></ul>
  28. 29. Overview of humoral response <ul><li>Activated T cell presents the antigen to a B cell </li></ul><ul><li>Cytokines activates the B cell </li></ul><ul><li>Activated B cells differentiate into plasma and memory cells </li></ul><ul><li>Plasma cells will produce the specific antibodies </li></ul>
  29. 30. Cell-mediated immune response <ul><li>Occurs when antigen displayed by APC activates Cytotoxic T cell </li></ul><ul><li>Cytotoxic cell can differentiate to Memory T cells or active cytotoxic T cells </li></ul><ul><li>Active against cancer cells and pathogens </li></ul><ul><li>Kills these cell through lysis </li></ul>
  30. 31. Antibodies <ul><li>Do not destroy antigens directly </li></ul><ul><li>Rather, neutralizes it or present it as a target for opsonization, agglutination, precipitation, or complement fixation, neutralization </li></ul>
  31. 32. Antibodies <ul><li>Opsonization- coating of antigens by antibodies to facilitate phagocytos </li></ul><ul><li>Neutralization- binds to the antigen and inactivates it </li></ul><ul><li>Agglutination- clumping of bacteria or virus to effectively neutralize or opsonize it </li></ul><ul><li>Complement fixation or precipitation- immune adherence occurs </li></ul><ul><ul><li>Microbes coated with antibodies and complement proteins adhere to BV walls </li></ul></ul>
  32. 33. The ABO blood type <ul><li>A and B are the antigens </li></ul><ul><li>Type A has antigen A and antibody B </li></ul><ul><li>Type B has antigen B and antibody A </li></ul><ul><li>Type AB has both antigen but no antibody </li></ul><ul><li>Type O has no antigen but has both antibody </li></ul><ul><ul><li>IgM not IgG </li></ul></ul>
  33. 34. Rh Factor <ul><li>IgG can cross the placenta </li></ul><ul><li>++ = + </li></ul><ul><li>+- = + </li></ul><ul><li>- - = - </li></ul>
  34. 35. Passive vs Active <ul><li>Passive </li></ul><ul><ul><li>short-lived </li></ul></ul><ul><li>Active </li></ul><ul><ul><li>Natural vs artificial </li></ul></ul>
  35. 36. Immunodeficiency vs Autoimmune disease

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